[PATCH v2 0/4] Renesas CPG/MSSR Reset Control Support

[PATCH v2 0/4] Renesas CPG/MSSR Reset Control Support

[Geert Uytterhoeven]

	Hi all,

This patch series adds reset control support to the Renesas Clock Pulse
Generator / Module Standby and Software Reset module, on the R-Car H3
and M3-W, RZ/G1M, and RZ/G1E SoCs.

  - Patch 1 amends the Renesas CPG/MSSR DT bindings for reset control,
  - Patches 2-4 add reset control to the Renesas CPG/MSSR driver.

Note that this patch series implements reset functionality only.
Actual reset policy is to be defined and implemented separately.

This is an optional feature, to be enabled explicitly using
CONFIG_RESET_CONTROLLER=y.  When enabled, an on-SoC device can be reset
easily using device_reset(), or by using the reset_control_*() API when
more fine-grained control is desired.

Possible use cases are (not exhaustive):
  - Reset a device before use, to make sure it's in a predefined state, and
    doesn't depend on earlier configuration by e.g. the boot loader,
  - Reset a device after detecting an anomaly,
  - Reset a device to verify suspend/resume is handled correctly by the
    driver in case the device would be part of a power domain on a
    different/future SoC.

Changes compared to v1:
  - Change oneline summary for binding update to refer to dt-bindings.
  - Add Acked-by, Reviewed-by,
  - Use variable bitmask in all reset operations, to make them more
    similar,
  - Dropped the DTS changes:
      - If CONFIG_RESET_CONTROLLER=y, they have a hard dependency on the
	driver patches (at least for USB on R-Car Gen3), so they can
	only go upstream in a later cycle,
      - The DTS changes will have to be respun anyway, to accommodate
	for changes in the DTS files between now and final upstreaming.

For your convenience, the driver and DTS changes (incl. dependencies)
are available in the topic/renesas-cpg-mssr-reset-driver-v2 resp.
topic/renesas-cpg-mssr-reset-dts-v1 branches of my topic/rcar-rst-v4
branch of my renesas-drivers git repository at
git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git

This has been tested on the R-Car Gen3 Salvator-X (H3 and M3-W) and the
R-Car M2-W (using out-of-tree driver modifications) Koelsch development
boards, by inspecting device register contents before and after reset,
and by comparing them with their documented reset values.

As this modifies a Renesas clock driver, I'll queue this up in my
clk-renesas-for-v4.11 branch, and will send a pull request later this
week.  

Thanks!

Geert Uytterhoeven (4):
  dt-bindings: clock: renesas: cpg-mssr: Document reset control support
  clk: renesas: cpg-mssr: Document suitability for RZ/G1
  clk: renesas: cpg-mssr: Rename cpg_mssr_priv.mstp_lock
  clk: renesas: cpg-mssr: Add support for reset control

 .../devicetree/bindings/clock/renesas,cpg-mssr.txt |   6 +
 drivers/clk/renesas/renesas-cpg-mssr.c             | 138 ++++++++++++++++++++-
 2 files changed, 138 insertions(+), 6 deletions(-)

-- 
1.9.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

[PATCH v2 1/4] dt-bindings: clock: renesas: cpg-mssr: Document reset control support

[Geert Uytterhoeven]

Document properties needed to use the Reset Control feature of the
Renesas Clock Pulse Generator / Module Standby and Software Reset
module.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - Change oneline summary to refer to dt-bindings.
---
 Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt b/Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt
index c469194129536332..f4f944d813081857 100644
--- a/Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt
+++ b/Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt
@@ -42,6 +42,10 @@ Required Properties:
 	Domain bindings in
 	Documentation/devicetree/bindings/power/power_domain.txt.
 
+  - #reset-cells: Must be 1
+      - The single reset specifier cell must be the module number, as defined
+	in the datasheet.
+
 
 Examples
 --------
@@ -55,6 +59,7 @@ Examples
 		clock-names = "extal", "extalr";
 		#clock-cells = <2>;
 		#power-domain-cells = <0>;
+		#reset-cells = <1>;
 	};
 
 
@@ -69,5 +74,6 @@ Examples
 		dmas = <&dmac1 0x13>, <&dmac1 0x12>;
 		dma-names = "tx", "rx";
 		power-domains = <&cpg>;
+		resets = <&cpg 310>;
 		status = "disabled";
 	};
-- 
1.9.1

[PATCH v2 2/4] clk: renesas: cpg-mssr: Document suitability for RZ/G1

[Geert Uytterhoeven]

The Renesas CPG/MSSR driver is already in active use for RZ/G1 since
commits c0b2d75d2a4bf6a3 ("clk: renesas: cpg-mssr: Add R8A7743 support")
and 9127d54bb8947159 ("clk: renesas: cpg-mssr: Add R8A7745 support").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
---
v2:
  - Add Acked-by.
---
 drivers/clk/renesas/renesas-cpg-mssr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c
index 6947482d48a55094..eb8534e5ebf3007d 100644
--- a/drivers/clk/renesas/renesas-cpg-mssr.c
+++ b/drivers/clk/renesas/renesas-cpg-mssr.c
@@ -43,7 +43,7 @@
  * Module Standby and Software Reset register offets.
  *
  * If the registers exist, these are valid for SH-Mobile, R-Mobile,
- * R-Car Gen 2, and R-Car Gen 3.
+ * R-Car Gen2, R-Car Gen3, and RZ/G1.
  * These are NOT valid for R-Car Gen1 and RZ/A1!
  */
 
-- 
1.9.1

[PATCH v2 3/4] clk: renesas: cpg-mssr: Rename cpg_mssr_priv.mstp_lock

[Geert Uytterhoeven]

The spinlock is used to protect Read-Modify-Write register accesses,
which won't be limited to SMSTPCR register accesses.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
---
v2:
  - Add Acked-by.
---
 drivers/clk/renesas/renesas-cpg-mssr.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c
index eb8534e5ebf3007d..f1161a585c57e433 100644
--- a/drivers/clk/renesas/renesas-cpg-mssr.c
+++ b/drivers/clk/renesas/renesas-cpg-mssr.c
@@ -98,7 +98,7 @@
  *
  * @dev: CPG/MSSR device
  * @base: CPG/MSSR register block base address
- * @mstp_lock: protects writes to SMSTPCR
+ * @rmw_lock: protects RMW register accesses
  * @clks: Array containing all Core and Module Clocks
  * @num_core_clks: Number of Core Clocks in clks[]
  * @num_mod_clks: Number of Module Clocks in clks[]
@@ -107,7 +107,7 @@
 struct cpg_mssr_priv {
 	struct device *dev;
 	void __iomem *base;
-	spinlock_t mstp_lock;
+	spinlock_t rmw_lock;
 
 	struct clk **clks;
 	unsigned int num_core_clks;
@@ -144,7 +144,7 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 
 	dev_dbg(dev, "MSTP %u%02u/%pC %s\n", reg, bit, hw->clk,
 		enable ? "ON" : "OFF");
-	spin_lock_irqsave(&priv->mstp_lock, flags);
+	spin_lock_irqsave(&priv->rmw_lock, flags);
 
 	value = readl(priv->base + SMSTPCR(reg));
 	if (enable)
@@ -153,7 +153,7 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 		value |= bitmask;
 	writel(value, priv->base + SMSTPCR(reg));
 
-	spin_unlock_irqrestore(&priv->mstp_lock, flags);
+	spin_unlock_irqrestore(&priv->rmw_lock, flags);
 
 	if (!enable)
 		return 0;
@@ -550,7 +550,7 @@ static int __init cpg_mssr_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	priv->dev = dev;
-	spin_lock_init(&priv->mstp_lock);
+	spin_lock_init(&priv->rmw_lock);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	priv->base = devm_ioremap_resource(dev, res);
-- 
1.9.1

[PATCH v2 4/4] clk: renesas: cpg-mssr: Add support for reset control

[Geert Uytterhoeven]

Add optional support for the Reset Control feature of the Renesas Clock
Pulse Generator / Module Standby and Software Reset module on R-Car
Gen2, R-Car Gen3, and RZ/G1 SoCs.

This allows to reset SoC devices using the Reset Controller API.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
v2:
  - Add Acked-by, Reviewed-by,
  - Use variable bitmask in all reset operations, to make them more
    similar.
---
 drivers/clk/renesas/renesas-cpg-mssr.c | 126 +++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)

diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c
index f1161a585c57e433..eadcbd43ff88319b 100644
--- a/drivers/clk/renesas/renesas-cpg-mssr.c
+++ b/drivers/clk/renesas/renesas-cpg-mssr.c
@@ -16,6 +16,7 @@
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/clk/renesas.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/mod_devicetable.h>
@@ -25,6 +26,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_clock.h>
 #include <linux/pm_domain.h>
+#include <linux/reset-controller.h>
 #include <linux/slab.h>
 
 #include <dt-bindings/clock/renesas-cpg-mssr.h>
@@ -96,6 +98,7 @@
 /**
  * Clock Pulse Generator / Module Standby and Software Reset Private Data
  *
+ * @rcdev: Optional reset controller entity
  * @dev: CPG/MSSR device
  * @base: CPG/MSSR register block base address
  * @rmw_lock: protects RMW register accesses
@@ -105,6 +108,9 @@
  * @last_dt_core_clk: ID of the last Core Clock exported to DT
  */
 struct cpg_mssr_priv {
+#ifdef CONFIG_RESET_CONTROLLER
+	struct reset_controller_dev rcdev;
+#endif
 	struct device *dev;
 	void __iomem *base;
 	spinlock_t rmw_lock;
@@ -494,6 +500,122 @@ static int __init cpg_mssr_add_clk_domain(struct device *dev,
 	return 0;
 }
 
+#ifdef CONFIG_RESET_CONTROLLER
+
+#define rcdev_to_priv(x)	container_of(x, struct cpg_mssr_priv, rcdev)
+
+static int cpg_mssr_reset(struct reset_controller_dev *rcdev,
+			  unsigned long id)
+{
+	struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
+	unsigned int reg = id / 32;
+	unsigned int bit = id % 32;
+	u32 bitmask = BIT(bit);
+	unsigned long flags;
+	u32 value;
+
+	dev_dbg(priv->dev, "reset %u%02u\n", reg, bit);
+
+	/* Reset module */
+	spin_lock_irqsave(&priv->rmw_lock, flags);
+	value = readl(priv->base + SRCR(reg));
+	value |= bitmask;
+	writel(value, priv->base + SRCR(reg));
+	spin_unlock_irqrestore(&priv->rmw_lock, flags);
+
+	/* Wait for at least one cycle of the RCLK clock (@ ca. 32 kHz) */
+	udelay(35);
+
+	/* Release module from reset state */
+	writel(bitmask, priv->base + SRSTCLR(reg));
+
+	return 0;
+}
+
+static int cpg_mssr_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
+	unsigned int reg = id / 32;
+	unsigned int bit = id % 32;
+	u32 bitmask = BIT(bit);
+	unsigned long flags;
+	u32 value;
+
+	dev_dbg(priv->dev, "assert %u%02u\n", reg, bit);
+
+	spin_lock_irqsave(&priv->rmw_lock, flags);
+	value = readl(priv->base + SRCR(reg));
+	value |= bitmask;
+	writel(value, priv->base + SRCR(reg));
+	spin_unlock_irqrestore(&priv->rmw_lock, flags);
+	return 0;
+}
+
+static int cpg_mssr_deassert(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
+	unsigned int reg = id / 32;
+	unsigned int bit = id % 32;
+	u32 bitmask = BIT(bit);
+
+	dev_dbg(priv->dev, "deassert %u%02u\n", reg, bit);
+
+	writel(bitmask, priv->base + SRSTCLR(reg));
+	return 0;
+}
+
+static int cpg_mssr_status(struct reset_controller_dev *rcdev,
+			   unsigned long id)
+{
+	struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
+	unsigned int reg = id / 32;
+	unsigned int bit = id % 32;
+	u32 bitmask = BIT(bit);
+
+	return !!(readl(priv->base + SRCR(reg)) & bitmask);
+}
+
+static const struct reset_control_ops cpg_mssr_reset_ops = {
+	.reset = cpg_mssr_reset,
+	.assert = cpg_mssr_assert,
+	.deassert = cpg_mssr_deassert,
+	.status = cpg_mssr_status,
+};
+
+static int cpg_mssr_reset_xlate(struct reset_controller_dev *rcdev,
+				const struct of_phandle_args *reset_spec)
+{
+	struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
+	unsigned int unpacked = reset_spec->args[0];
+	unsigned int idx = MOD_CLK_PACK(unpacked);
+
+	if (unpacked % 100 > 31 || idx >= rcdev->nr_resets) {
+		dev_err(priv->dev, "Invalid reset index %u\n", unpacked);
+		return -EINVAL;
+	}
+
+	return idx;
+}
+
+static int cpg_mssr_reset_controller_register(struct cpg_mssr_priv *priv)
+{
+	priv->rcdev.ops = &cpg_mssr_reset_ops;
+	priv->rcdev.of_node = priv->dev->of_node;
+	priv->rcdev.of_reset_n_cells = 1;
+	priv->rcdev.of_xlate = cpg_mssr_reset_xlate;
+	priv->rcdev.nr_resets = priv->num_mod_clks;
+	return devm_reset_controller_register(priv->dev, &priv->rcdev);
+}
+
+#else /* !CONFIG_RESET_CONTROLLER */
+static inline int cpg_mssr_reset_controller_register(struct cpg_mssr_priv *priv)
+{
+	return 0;
+}
+#endif /* !CONFIG_RESET_CONTROLLER */
+
+
 static const struct of_device_id cpg_mssr_match[] = {
 #ifdef CONFIG_ARCH_R8A7743
 	{
@@ -591,6 +713,10 @@ static int __init cpg_mssr_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
+	error = cpg_mssr_reset_controller_register(priv);
+	if (error)
+		return error;
+
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v2 1/4] dt-bindings: clock: renesas: cpg-mssr: Document reset control support

[Rob Herring]

On Wed, Jan 25, 2017 at 10:15:00AM +0100, Geert Uytterhoeven wrote:
> Document properties needed to use the Reset Control feature of the
> Renesas Clock Pulse Generator / Module Standby and Software Reset
> module.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> v2:
>   - Change oneline summary to refer to dt-bindings.
> ---
>  Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt | 6 ++++++
>  1 file changed, 6 insertions(+)

Acked-by: Rob Herring <robh@kernel.org>